Pressure-relieving means for drawing presses



Patented Apr. 7, i925.

o Tar as Pl h BERGER T. ANDRETN' AND JOHN DILOT, OF MILWAUKEE,\VISCDNSIN, ASSIGNGRS T9 A. 0. SMITH CORPORATION, OF MILWAUKEE,'WISCGNSI- ACOREOR-ATIGN OE NEW YORK.

PRESSURE-EELIEVING MEANS FOR DRAWING- PRESSES.

Application filed October 17, 1924. Serial No. 744,097.

To all whom it may concern:

Be it known that we, Bnacnn TonvliLD 'Axniunt and JoHN Dino'r, subjectsof the King of Sweden, but each having declared an intention of becominga citizen of the Uniten States, and both being residents of the city ofMilwaukee, county of Milwaukee, and State of .Jisconsin, have inventedcertain new and useful Improvements in Pressure-Relieving Means forDrawing Presses;

and we do declare the following" to be a clear, exact, and completedescription thereof, such as will enable others skilled in the art towhich the invention pertains to make and use the same, reference beinghad to the accompanying drawing for an illustration of someconstructional forms in which our improvement has been embodied.

in the operation of presses for drawing sheet-metal contoured blanks ofthick gage into shape aslchannels or other forms, it sometimes happensthat by reason of the inelasticity of the metal sheet, the forming dieforces the latter into the matrix of the press with dificulty, theresistance to com pression of the metal sheet creating a very greatfrictional orwedging engagement with the die and matrix, which can beovercome only by the exertion of excessive power,

This action imposes severe strains upon the I mechanism of the press,and damage sometimes results, the repalr of which is costly.

Our invention is designed to overcome the.

objections referred to, and by making use of such invention, therequirement for the employment of such excessive power is avoided, andthe consequent liability to damage to the drawing press is eliminated.

These desirable results we achieve by constructing the matrix of thepress so that one wall thereof will yield when the resistanceencountered in the drawing operation exceeds the maximum of powernecessary to the proper operation of the press. Such constructionincludes the arrangement of a pressure relieving or give-way devicebetween the outer side of one wall of the matrix and the adjacentparallel wall of the channel of the bed of the press in which the matrixis placed.

The give-way device referred to is composed of two plates provided ontheir opposed faces with tongues and grooves which are adapted toregister and engage with each to yield when the resistance becomesexcessive.

The character and composition of the interposed plate are such that whenthe nor maljmaximum resistance of the metal blank then being drawn isexceeded, the tongues of the opposed plates will act with a shearingaction upon the interposed plate and sever the same, so that the tonguesof the oppositely arranged plates may enter the grooves alignedtherewith, so as to permit the movable wall of the matrix to recede fromits fixed, operative position, and thereby relieve the press of theinjurious st 'ains sometimes incident'to its operation.

The formation of the interposed platewill be determined by theascertained maximum strains which it will be required to ltfiSil beforethe shearing act-ion referred to takes place. r

The invention in some of its embodiments will now be specificallydescribed, and the novelty thereof will be pointed out in the appendedclaims.

Referring now to the drawing which ac companies this specification:

Figure 1 is a transverse vertical sectional view of the bed of a drawingpress, in perspective,'and showing one form of our invention in itsoperative relation thereto; and Fig. 2 is a longitudinal sectional viewshowing another form of the invention as applied to a straining rod, thefunction and operation, that of resisting expansive strains, being thesame in each case.

In the drawing, the numeral 10 represents the bed of a drawingpress,-which may be provided with a sunken matrix 11, one wall 12 ofwhich is mounted so as to have a slight outward yielding movement whenexcessive the channel in the bed of the press which receives the matrixis widenec so as to perout the insertion of a yielding or give-waydevice between the movable wail of the ma-- trix and the adjacentportion of the-bed of the press.

This yielding or give-way device which serves as a means for relievingthe pressure is'composed of two hardened metal plates or members 13 and14, matched on their opposing faces so as to provide sharp corneredtongues 15 and grooves 16, designed t'o'in'terlock with each other, butnormally separated by the interposition of a softer metal plate 17. Thenature and char cteristics of the said plate will be suchas to enableittore- 'sist the normal strains exerted in the drawing operation, andsosustain the matched plates 18 and 14; in their separated positions.

However, when the strain encountered in the drawing operation exceedsthe normal strain above referred to, the cutting corners of the tongues15 ot the opposed plates will act witha shearing action upon theinterposed plate 17, and by severing the same willbring about a releaseof the excessive pressure, and thus free the press from liability tothefdamage heretofore:encounteredwhen the resistance is excessive. A.compressible wooden strip 18 may be placed in the groove on'the u ermostton 'ue of the plate 14 to close the gap and prevent .lodgment thereinof foreign matter.

The bed of the press may be bored laterally at one side for thereception of a bolt 19, which passes through perforations in the plates13 and 14, and is threaded into a perforation in the movable wall .12of'the matrix, so as to retain the said wall in a relatively fixed positon, but permit the same to moveoutwardly when excessive pressure .isexerted. A loose sleeve or bushing. 20 may be inserted inregisteringopenmgs 1n the plates. 13and 14., and the shank-of the bolt19 may pass through such sleeve 'or bushing.

Also the-plates 13 and 1a and theinterposed plate -17-may'he connectedso asto form a unit by IXIGZLDSOf screws 21, free to'move in aperforation in'one of the plates and threaded into the other, thev'saidsci'ew'being passedthrough registering perlorations iii-the interposedplate 17. The. number of screws 21 will be such as may be desirable toconstitute the unit construction of the pres sure relievingdevices.

In Fig. 2 we have shown a modification in the application of our device.In this figure the numeral 25 indicates a straining rod 'oinin nuts 26and 27 of a ress. Be-

tween-the part 27 and the nut 28 a1 yielding or give-way device formedof hardened metal discs 29 and 30, the opposed faces of which areconstructedwith matched tongues and grooves,arranged in concentriccircles, is provided. A washer or cap 31 may be placed between theyielding device and the nut 28. The operation of this construction willbe understood from what has been said in relation to the contructionshown in Figs 1.

hardened metal plates provided with registerington 'ues and groovesupontheir'opposed faces, in combination witha plate of softer metalarranged between the hardened plates and subjected to shearing'action'when the ,pressure exerted upon the hardened plates exceeds the normalresistance ofthe interposed plate.

'3. In a drawin' oress a bed )rovi'ded b 7 i with a channel forming amatrix, onewall of which latter is movable in the channel,

and apressure relieving device arranged between the movable wall and theadjacent channel wall, such pressure relieving device comprisinghardened metal platesprovided on tieir opposed faces with cuttin edges,

in combination with a plate of setter metal arranged between thehardened plates and subjected to shearing action when the pressureexerted upon the'hardened plates e2;- ceeds the normal resistance of theinterposec plate.

4-. In a drawing press, a 'bed provided with a channel forming a matrix,one wall ot which latter is movable outwardly of the channel, a pressurerelieving device arranged between themovable wall and the adjacentchannel wall, such pressure relie ing device comprisinghardened metalplates pro vided on their opposed faces with cutting edges, incombination-with a plate 01 softer metal disposed between the hardenedplates and subjected to shearing action whenthe pressure upon thehardened plates exceeds the nOrinalresistance ofthc interposed plate,and means for restraining the inward movement ofthe' movable'wall of thematrix.

In testimony whereof, wehave signed'our names atlMilwaukee, this 10thday of @cto- 'ber, 1924.

B. T. ANDREN.

J. 'DILGT. VVitness:

JV. F. 'lVooLAnD.

